I have used Calico Coatings in Denver, NC to do my turbocharger stuff, they do NASCAR work as well around here, just throwing them out as another ceramic coating source.
http://www.calicocoatings.com/ Used them several times, no issues with thier coatings, and generally the turbo pipes run hotter than normal exhaust, I've track-tested them under pretty severe conditions (7400 RPM, lap after lap, road courses down South).
